code: def test_optional_tokens(self):
      data = (
          "machine host.domain.com",
          "machine host.domain.com login",
          "machine host.domain.com account",
          "machine host.domain.com password",
          'machine host.domain.com login "" account',
          'machine host.domain.com login "" password',
          'machine host.domain.com account "" password',
      )
      for item in data:
          nrc = self.make_nrc(item)
          self.assertEqual(nrc.hosts["host.domain.com"], ("", "", ""))
      data = (
          "default",
          "default login",
          "default account",
          "default password",
          'default login "" account',
          'default login "" password',
          'default account "" password',
      )
      for item in data:
          nrc = self.make_nrc(item)
          self.assertEqual(nrc.hosts["default"], ("", "", ""))
  
imports: import netrc, os, unittest, sys, textwrap
  from test.support import os_helper
label_desc: Use image node_id 5 for calling the NetrcTestCase obj's underlying member method code with example usage: obj.test_optional_tokens() without return types